Prevention of PCDD/F formation and minimization of their emission at the stack of a secondary aluminum casting plant.
Results of an extensive 5 year study on a full-scale plant with the specific aim to investigate polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzo furan (PCDF) formation and release in a secondary aluminum casting plant are reported. PCDD and PCDF concentrations were evaluated for all the gaseous and solid streams (no liquid stream was present) as well as for the flue gas upstream and downstream of every single unit of the flue gas cleaning system. The study highlights PCDD and PCDF formation particularly in the narrow 320-360 degrees C range. To prevent formation reactions and/or minimize PCDD and PCDF concentration at the stack, effects of the fabric filter substitution, a quenching chamber and a postcombustor installation together with working conditions are investigated. The flue gas cleaning system results in PCDD and PCDF emission at stack of 0.1-0.2 ng I-TEQ/N m3 and in a mass flow of 250-550 nmol/h. The total PCDD and PCDF release into the environment is 0.06 g I-TEQ/yr and the corresponding emission factor, 0.35 microg I-TEQ/ton. It is shown that the global effects of the technological innovation on the reaction mechanisms are the prevention of PCDD/F formation by de novo synthesis and the minimization of their emission.
Pitea
Demetrio
D
Dipartimento di Scienze dell'Ambiente e del Territorio, Università di Milano Bicocca, Piazza della Scienza 1, 20126 Milano, Italy. demetrio.pitea@unimib.it
Bortolami
Michele
M
Collina
Elena
E
Cortili
Gabriele
G
Franzoni
Francesco
F
Lasagni
Marina
M
Piccinelli
Elsa
E
D000535:Aluminum / Q000737:chemistry*; D001572:Benzofurans / Q000138:chemical synthesis*; D002244:Carbon / Q000737:chemistry; D005374:Filtration; D005740:Gases / Q000737:chemistry; D007221:Industry; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D013696:Temperature
D001572:Benzofurans; D005740:Gases; D000072317:Polychlorinated Dibenzodioxins; D002244:Carbon; C023614:dibenzofuran; D000535:Aluminum